<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        * {
            border: 0;
            margin: 0;
            padding: 0;
            font-family: Arial, Helvetica, sans-serif;
        }

        /* 
            媒体查询(常用)
            小于768  超小屏幕 max-width=768px
            大于768  小屏幕   min-width=768px
            大于992  中型屏幕 min-width=992px
            大于1200 按屏幕   min-width=1200px
        */

        @media (min-width: 1200px) {
            body {
                min-height: 100vh;
                background-color: #abefe9;
            }

            body>div {
                margin: 5px;
                border: #bfa 3px solid;
                background-color: #FFCCCC;
            }
        }

        /* 
            (max-width:1200px) and (min-width:768px)  表示同时满足
            (max-width:1200px) , (min-width:768px)    表示满足其一
        */
        
        @media(max-width:1200px) and (min-width:768px) {
            body {
                min-height: 100vh;
                background-color: #000;
                color: white;
                font-size: 50px;
            }

            body>div {
                background-color: #f90;
            }
        }



        hr {
            background-color: red;
            height: 1px;
            border: 0;
        }

        .d1 {
            font-weight: bold;
            display: inline-block;
            border-radius: 5px;
            padding: 10px 20px;
            color: black;
        }
    </style>
</head>

<body>
    <br>
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
    chuan's
    <div class="d1">
        Repositories
    </div>
</body>

</html>